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The blood concentration of 1,8-cineole and its metabolites was measured in six male brushtail possums while they voluntarily fed on diets laced with varying concentrations of cineole for 3 d. On the third day, blood samples were collected during and after each bout of feeding for 3 hr. Blood cineole was measured by using headspace solid-phase microextraction (SPME), while cineole metabolites were measured by liquid–liquid extraction followed by gas chromatography-mass spectroscopy. Feeding patterns were measured by continual recording of residual food weight and time. Cineole absorption was rapid, resulting in a peak blood concentration at the end of each feeding bout. The blood concentration of cineole did not exceed a critical value (51.8 ± 14.1 ìmol/l) regardless of the concentration in the diet. Food and, therefore, cineole intake was regulated. The amount of food ingested in the first feeding bout decreased from 236 ± 52 g on the control diet to 36 ± 20 g on the 4% cineole diet. The amount of cineole ingested in the first bout (1.18 ± 1.10 g) was the same regardless of the dietary concentration and was controlled by the size of the meal. Total food eaten during the 7-hr feeding session decreased by 64% from 368 ± 94 g (control diet) to 131 ± 52 g (4% diet). Total cineole intake increased from 2.47 ± 0.60 g (1% diet) to 5.05 ± 2.41 g (4% diet). Cineole metabolites accumulated throughout the sampling period and were generally still rising at the end of blood sampling period. Blood levels of metabolites were at least 10-fold higher than cineole levels. The immediate control of feeding seems to be regulated by blood levels of cineole, whereas metabolites are likely to be more important in regulating the chronic ingestion of cineole.

Item Type:	Refereed Article
Keywords:	Absorption - antifeedant - blood concentrations - Brushtail possum - 1,8-cineole - cineole metabolites - plant secondary metabolites - terpenes
Research Division:	Medical and Health Sciences
Research Group:	Pharmacology and Pharmaceutical Sciences
Research Field:	Basic Pharmacology
Objective Division:	Expanding Knowledge
Objective Group:	Expanding Knowledge
Objective Field:	Expanding Knowledge in the Environmental Sciences
Author:	Boyle, RR (Dr Rebecca Boyle)
Author:	McLean, SR (Professor Stuart McLean)
Author:	Brandon, S (Mrs Susan Brandon)
Author:	Wiggins, NL (Dr Natasha Wiggins)
ID Code:	38244
Year Published:	2005
Web of Science® Times Cited:	30
Deposited By:	Pharmacy
Deposited On:	2005-08-01
Last Modified:	2011-05-12
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